A judge yesterday ordered a business manager for Marlon Brando (search) and his son Christian to stay away from one of the defense witnesses in the Robert Blake (search) murder case.

Cowlitz County (Washington state) Judge David R. Koss told longtime Brando aide Mary JoAn Corrales to steer clear of Dianne Mattson (search) and not have her followed.

"[Corrales] is restrained from making any attempts to keep [Mattson] under surveillance. [Corrales] is restrained from making attempts to contact [Mattson]," states the order signed by Koss in Kelso, Wash.

Mattson is poised to testify for Blake when his trial for allegedly murdering wife Bonny Lee Bakley (search) begins in March.

Mattson, once a friend of Christian Brando - who lives in Kalama, Wash., near Mattson - has said she overheard a speakerphone conversation between her former pal and stuntman Ronald "Duffy" Hambleton in which Brando allegedly made threats against Bakley.

The conversation allegedly took place three weeks before Bakley's murder in May 2001. Blake's defense plans to use Mattson's testimony to show others wanted to kill Bakley, a notorious con artist who once tried to hook Christian Brando into a relationship.

Hambleton is a prosecution witness. He's already testified at Blake's preliminary hearing that the former "Baretta" star wanted to hire him to kill Bakley.

Mattson claims she fears that Corrales or another representative of the Brandos will try to rough her up before she testifies.

Mattson said she was grocery shopping near her Kelso home on Sept. 6 when Corrales chased her through the market.

Corrales cornered and pinned Mattson with a shopping cart near some coolers and assailed her to a barrage of threats and epithets, according to court documents.

Corrales allegedly threatened Mattson: "We have attorneys and we will destroy you! Keep your mouth shut if you know what's good for you!"

"She feels very relieved," said Mattson's California-based lawyer Brian Oxman after gaining the protective order. "She feels this was an attempt to intimidate her [from testifying]."

Corrales' lawyer David Seeley said Mattson is exaggerating the incident.

"It didn't take place the way Mattson and her media-hungry lawyer said it did," he said. "There was a conversation between two people who have known each other . . . No one was chasing anyone."